Ion beam synthesis of SiC by C implantation into SIMOX(1 1 1)

We report the conversion of a 65 nm Si(1 1 1) overlayer of a SIMOX(1 1 1) into 30-45 nm SiC by 40 keV carbon implantation into it. High temperature implantation (600 deg. C) through a SiO2 cap, 1250 deg. C post-implantation annealing under Ar ambient (with 1% of O2), and etching are the base for the present synthesis. Sequential C implantations (fluence steps of about 5 x 1016 cm-2), followed by 1250 deg. C annealing, has allowed to estimate the minimum C fluence to reach the stoichiometric composition as ∼2.3 x 1017 cm-2. Rutherford Backscattering Spectrometry was employed to measure layer composition evolution. A two-sublayers structure is observed in the synthesized SiC, being the superficial one richer in Si. Transmission electron microscopy has shown that a single-step implantation up to the same minimum fluence results in better structural quality. For a much higher C fluence (4 x 1017 cm-2), a whole stoichiometric layer is obtained, with reduction of structural quality.